The present invention relates to an adjustable wrench which is adapted to engage a variety of non-circular fasteners, and in particular hex nuts and hex bolt heads.
Adjustable wrenches of the general type with which the present invention is concerned are well known. Examples of such adjustable wrenches are shown, for example, in U.S. Pat. No. 2,912,891, issued Nov. 17, 1959, to T. Neff, U.S. Pat. No. 3,204,497, issued Sep. 7, 1965, to L. R. Dinkler, U.S. Pat. No. 4,520,699, issued Jun. 4, 1985, to M. Jeremic, U.S. Pat. No. 4,967,613, issued Nov. 6, 1990 to R. E. Cone, and U.S. Pat. No. 5,415,064, issued May 16, 1995 to C-H. Chang.
The standard arrangement for such adjustable wrenches is to have two jaws, one fixed with respect to the wrench handle and the other movable with respect to the fixed jaw. Typically, as is illustrated in the aforesaid patents, the movable jaw has an actuator element onto which an external male thread is formed, the movable jaw being attached to the actuator element by any one of a variety of means. The handle includes a knurled knob which has a complementary female threaded aperture extending therethrough, through which the male threaded actuator element extends so as to engage the female threads. Manual rotation of the knob, as by a user's thumb, causes the rotary motion of the knob to be translated into linear motion of the movable jaw, so as to selectively either tighten the jaws onto the element to which torque is to be applied or to loosen the jaws therefrom.
Among the principal objectives of the prior art adjustable wrenches, including those configurations shown in the aforementioned patents, are to produce an adjustable wrench which is strong, easy to use, can be used in close quarters, and fully grips the object to which torque is to be applied by at least half of its torquing surfaces. While all of these wrenches have been successful in achieving some or all of these objectives to a greater or lesser degree, they all suffer from a deficiency inherent in the utilization of the male-female thread relationship referred to above, in which the male thread is externally formed on the element which must pass through the interior of the knurled knob which is rotated in order to make the jaw adjustments. Because of the tolerances required in the assembly line manufacture of such adjustable wrenches, the "play" between these two element is sufficient to carry over into the gripping of the fastener to permit some "play" in the handle in use when the jaws grip the hex nut or bolt or other object to which torque is to be applied.
Even U.S. Pat. No. 4,967,613, referred to above, is not entirely successful in solving this problem, even though the adjustable wrench of this patent utilizes dovetail supports for alignment purposes for the moving elements, an obviously expensive structure. The use of dovetail supports would appear to be a satisfactory solution to this problem. However, because of the comparatively short length of the dovetail surfaces in contact at any one time in the design illustrated in Pat. No. 4,967,613, and the tolerances necessarily involved in the mass production of such a device, the device has not entirely solved the problem of "play" referred to above.
Consequently, a need still exists for an improved adjustable wrench which will be strong, easy to use, can be used in close quarters, and can fully grip the object to which torque is to be applied on at least half of its torquing surfaces without excessive play while avoiding the design deficiencies inherent in the prior art structure of a movable jaw with an actuator element onto which an external male thread is formed as the driven element, a handle having a knurled knob with a complementary female threaded aperture extending therethrough as the drive element, through which the male threaded actuator element extends so as to engage the female threads.